Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Projecting images onto a screen is broadly used for presentation purposes and the like. During a presentation, a presenter may “electronically write”, or mark, on the projected image to emphasize on a particular point or make notes for future reference. For example, when a Microsoft® PowerPoint® presentation is projected onto a screen, the presenter may directly mark on one of the presentation slides by using the PowerPoint editing functions. The updated slide, which contains the presenter's inputs, can then be projected onto the screen.
Alternatively, the presenter may rely on a screen (e.g., a white board) capable of electronically capturing his/her writings and drawings. Such a screen may be equipped with physical-contact sensors or light sensors, and the screen can be configured to capture and display the presenter inputs. For example, suppose the screen can detect physical contact. During presentation, the presenter can use a hard object to press against the screen. The signal generated by the pressing is then captured by the screen and utilized for making marks on the image to be displayed.